Concrete forms have long been used as formwork for the construction of concrete structures, such as the walls or floors of a building. Traditional form systems typically entail setting up two spaced apart form panels and pouring concrete into the space created between the panels. After the concrete hardens, the forms are removed, leaving the cured concrete wall. Traditional systems, however, have several drawbacks including the time required to erect the forms, the time for the concrete to cure, and the time to take down the forms, making the process expensive and labour-intensive.
Many modular insulated concrete form (ICF) systems are been developed to overcome the drawbacks of traditional form systems. Modular ICF systems typically comprise setting up the form system, generally classified as either “block” or “panel” systems, pouring the concrete into the space between the forms and leaving the form in place. As such, the insulating form becomes a permanent part of the structure after the concrete cures. Modular ICF systems are increasingly popular because they serve to insulate the concrete structure in addition to containing the fluid concrete as it solidifies, reducing the time and cost required to create the structure.
“Block” ICF systems typically comprise preassembled blocks having two expanded polystyrene (EPS) foam members connected together with ties or webs, wherein the ties or webs create a cavity between the two foam members for receiving fluid concrete. The ties or webs connecting the panels together can be molded to the foam members during the manufacturing process. As such, block ICF systems are often referred to as “fixed-tie” systems, and the blocks are installed at the construction site by stacking the blocks one on top of another (in a staggered fashion similar to the assembly of a brick wall). Blocks are then affixed together by fastening the webs of one block to the webs of an adjacent block manually, often with cable-ties.
As a result the manufacturing process, however, the size, shape and cavity size of EPS blocks are limited by the molding machine used to create the block. Further, stacking multiple blocks one atop the other creates a plurality of joints between the blocks, reducing the overall strength of the wall, increasing the risk of vertical or horizontal skewing, and making the incorporation of design elements, such as windows, doors, corners etc., difficult.
“Panel” ICF systems are often constructed to be longer (e.g. taller) than block systems for faster installation. A number of variations of modular panel ICF systems and methods for their use have been developed. Typically, such panel ICF systems use two opposed EPS foam panels manufactured from commercially available pre-formed expanded polystyrene slabs connected together with spacers to form a cavity for receiving concrete between the two panels. The polystyrene slabs are cut down to size using a hot-wire cutting process and the spacers connecting the panels together are extruded to the desired size/shape from plastic materials before being affixed to the panels. The spacers are either fastened to the interior surface of the panels, or extend through the panels themselves, to create the cavity therebetween. Spacers or “bridging members” are known to have varying shapes, sizes, and strengths, often being used to reinforce the building structure.
Panel ICF systems allow for the manufacture of larger panels, resulting in easier and faster installation at the construction site. The panels can also be stacked one on top of the other (many stories high) to form the concrete structure. Larger panels also reduce the number of joints between panels and the risk of the wall skewing, increasing the overall strength of the wall. Design elements, such as doors and corners, are also easier to incorporate in panel structures. Although the prior art proposes variations to achieve improvements with concrete form systems, however, many drawbacks still exist.
By way of example, Canadian Patent Application No. 2,597,832 describes a panel ICF system where two panels are connected together by individual internal spacers coupled to individual external studs protruding through the panel and held together by external support straps. Both panels are pre-formed and cut from an EPS slab to the desired panel size and shape, including the apertures through the panels for receiving the internal spacers/external studs. At the construction site, the worker must first line the two panels up then manually position each individual spacer into the apertures of both panels. This laborious process requires that cutting of the panels be extremely precise to achieve proper alignment of the spacers/studs and apertures for receiving same.
A similar system is described in U.S. patent application Ser. No. 12/200,846, however the individual spacers are mounted on a common spacer “frame” (extending vertically up the interior surface of the panel). Use of the spacer frame provides simpler installation than having to align a plurality of individual spacers. Although somewhat easier to install, the panel system nonetheless requires detailed positioning and cutting of the pre-formed panels and the apertures therethrough for receiving the internal spacer “frame” and corresponding studs. The system is also held together by external connector straps.
Despite the benefits provided by known panel ICF systems, the manufacturing process of cutting panels from standard EPS creates waste of excess material and must be accurate (e.g. placement of apertures for receiving spacers, and positioning of spacers with corresponding external stud and strapping) for on-site assembly of the panel structure to be efficient and successful. One further disadvantage common to the prior art is the limited ability to readily vary the spacing between the side panels of the forms, and therefore the thickness of the concrete wall.
There is a need for an improved ICF panel system and a process of making same, the system being capable of being manufactured into one continuous section for easy installation in the structure. It is desired that such a system could provide an internal stabilizing frame for use as a mold to receive expandable polystyrene material, such that the frame becomes integral to the panels molded thereto. Such a system may provide for easy assembly of pre-formed panels at the construction site, without the panels being limited in size or shape.